server.js

const path = require('path');
const express = require('express');
const cors = require('cors');
const { spawn } = require('child_process');

const app = express();
const PORT = process.env.PORT || 3006;

app.use(cors());
app.use(express.json({ limit: '2mb' }));
app.use(express.static(path.join(__dirname, 'public')));

const SYSTEM_PROMPT =
  "You are a helpful assistant. Help answer the user's question.";

function buildPrompt(messages) {
  let prompt = `${SYSTEM_PROMPT}\n\n`;

  for (const message of messages) {
    if (!message || typeof message.content !== 'string') {
      continue;
    }

    if (message.role === 'user') {
      prompt += `User: ${message.content}\n`;
    } else if (message.role === 'assistant') {
      prompt += `Assistant: ${message.content}\n`;
    }
  }

  prompt += '\nAssistant:';
  return prompt;
}

app.get('/health', (req, res) => {
  res.json({ status: 'ok', message: 'Claude Code bridge is running' });
});

app.post('/chat', (req, res) => {
  const { messages } = req.body || {};

  if (!Array.isArray(messages)) {
    return res.status(400).json({
      success: false,
      error: 'Invalid payload. Expected { messages: [...] }.'
    });
  }

  const prompt = buildPrompt(messages);

  try {
    const claude = spawn('claude', ['-p', '--output-format', 'text'], {
      stdio: ['pipe', 'pipe', 'pipe']
    });

    let stdout = '';
    let stderr = '';

    claude.stdout.on('data', (data) => {
      stdout += data.toString();
    });

    claude.stderr.on('data', (data) => {
      stderr += data.toString();
    });

    claude.on('close', (code) => {
      if (code !== 0) {
        return res.status(500).json({
          success: false,
          error: stderr || 'Claude Code exited with an error.'
        });
      }

      res.json({
        success: true,
        message: stdout.trim()
      });
    });

    claude.on('error', (err) => {
      res.status(500).json({
        success: false,
        error: `Failed to run Claude Code: ${err.message}. Make sure 'claude' CLI is installed and authenticated.`
      });
    });

    claude.stdin.write(prompt);
    claude.stdin.end();
  } catch (error) {
    res.status(500).json({
      success: false,
      error: error instanceof Error ? error.message : 'Unexpected error.'
    });
  }
});

app.listen(PORT, () => {
  console.log(`Claude Subscription Chat running at http://localhost:${PORT}`);
});